The present invention relates generally to the field of arc welding systems, and more particularly to an arc welding torch adapted to receive a cylindrical metal electrode.
TIG (Tungsten Inert Gas) welding (also known as gas tungsten arc welding, GTAW, or HELIARC) is a type of arc welding process in which an electric arc is maintained between a cylindrical metal electrode and a metal object. The heat generated by the arc produces localized melting of the metal object. The electrode, typically tungsten, is secured to a torch to enable a user to direct the electrode and establish the point of contact between the electrode and the object. TIG welding may be performed with or without the addition of a filler metal. Typically, the weld puddle and the area surrounding the weld puddle are protected from the atmosphere by an inert gas. The inert gas prevents rapid oxidation of the weld and the surrounding metal.
A ground cable is used to connect the metal object to the power supply. When the electrode is placed in close proximity to or against the metal object, the electrode in the welding handle completes an electrical circuit between the power supply and the metal object, allowing electrical current to flow through the electrode and metal object. The electrical current produces an arc between the electrode and the metal object. The heat of the electric arc melts the metal object in the region surrounding the electric arc. A filler material may be placed against the molten portion of the object, melting the filler material and allowing the molten filler material to merge with the molten object. Once the electrode is drawn away from the metal object, the circuit is broken and the molten mass begins to cool and solidify, forming a weld.
The electricity for the welding process is provided by a power source through a welding cable coupled to the torch. Typically, the power source is a constant voltage AC, DC, or a combination AC/DC source. In addition, a TIG welding cable typically is adapted to transport the inert gas to the torch. Furthermore, the TIG welding process typically generates a substantial amount of heat in the electrode. Consequently, cooling fluid may be used to cool the torch. Thus, a welding cable for a TIG welding system may transport electricity, gas, and cooling fluid.
A tungsten electrode typically is secured to a TIG welding torch by a collet, a collet body, and a backcap. To secure the electrode to a welding torch, the electrode is inserted through the collet and collet body. Typically, the collet body is threaded into a front portion of the torch head and the backcap is threaded into the rear portion of the torch head, with the collet located between the collet body and backcap. As the backcap is threaded into the torch head, the backcap urges the collet against the interior of the collet body. The collet body is adapted to compress the collet against the electrode as the collet is driven against the collet body, thereby securing the electrode to the torch. In addition, the collet body is adapted to enable gas to flow into the rear end of the collet body around the electrode and out through holes in the side of the collet body.
There are a number of problems associated with the use of a collet and collet body to secure an electrode to a welding torch. One problem is that the collet may become misaligned during assembly, resulting in the electrode becoming misaligned. A misalignment of the electrode or collet may produce non-uniform gas flow through the welding torch. In addition, a collet typically is a relatively small object that may be easily dropped during assembly or replacement of an electrode. Furthermore, for each diameter of electrode there is an appropriately sized collet and collet body. Therefore, the correct collet and collet body must both be determined and selected by a user for each installation of an electrode, thereby increasing the difficulty and time required to install an electrode in a welding torch, especially when changing from an electrode of one diameter to an electrode of another diameter.
A need exists for a technique to enable an electrode to be secured to a welding torch using fewer parts. In addition, a need exists for a technique to enable a user to install an electrode in a welding torch more easily than existing techniques that utilize a separate collet and a collet body. Furthermore, a need exists for a technique to enable a user to replace electrodes of different diameters more easily than existing techniques that utilize a collet and a collet body. There also exists a need for a device that enables an electrode to be secured to a welding torch consistently in a concentric orientation to provide proper shielding gas flow through the welding torch.